Let me share a story.....
About 4 years ago, I was a Kawasaki test rider for the new KLR. I was given the bike to keep for a full year to flog, draw some conclusions and write about them. An additional manufacturer decided to enter the testing and fray.....a oil blending company. They had just released a new 100% synthetic 10w40 and wanted a lot of real life use and lab testing. I obliged......
Here is what I learned..... The operators manuals for 2500 and 3500 pick up trucks are spot on. They provide standard service intervals and severe service intervals. And there is good reason. If a truck is being operated in high heat, lots of dust and pulling heavy loads, it needs attention much more often than a truck that never pulls a trailer and runs down the highway.
We should apply this wisdom and logic to our service intervals on our motorcycles.
The first 3,000 miles on the KLR were nearly all highway, with a lot of easy cruising. The next 1,500 miles were 7 days of my riding, pushing the bike off-road with a heavy load through some of the toughest trail that Colorado could throw at it. High mountain pass climbs pushed the engine temps to their limits and tested the clutch.
At the 3,000 mile OCI, the oil was solid in its viscosity and additives and TBN. It looked like nearly new oil.
We dumped that run of oil and did a fresh change for the trip. Upon coming home from the off-road trip and 1,500 miles later, the oil was dumped and tested and it was a disaster. 40wt had dropped to 20wt and there was little TBN left.
Same bike....same oil....same filter..... amazingly different results based upon riding conditions.
6 months later, just to test.... I did a similar trip as the 1,500 mile off-road, but ran Shell Rotella T6 5w40 Synthetic. (Because this has always been my 'go to' oil for nearly everything.) And the results were similar. Viscosity dropped to a high 20wt and the oil was thrashed. The next run....I went 5,000 miles on the Rotella T6, of mostly pavement and dirt road cruisers......and the oil tested out great.
Fellas....its all about riding style and riding conditions as to when someone should change their oil.
Granted.....its about the bike as well. If the bike has a wet clutch and shared sump with the tranny, the oil will go faster. On my 2005 GS and with my previously owned 2004 RT with a dry clutch and separate transmission sump......the bikes are very, very easy on oil and I have no issues going 6-8k miles on top shelf synthetic......and if I had to run 10k, I would not fret.
But when I ride my KTM 950 or my Yamaha WR426 in harsh conditions, they sometimes get an oil change at the 500-1,000 mile mark.
Just my two cents......